Method of manufacturing mixers

ABSTRACT

A method for fabricating a unitary mixer is disclosed, said method comprising the steps of determining three-dimensional information of the unitary mixer having at least one swirler, converting the three-dimensional information into a plurality of slices that each define a cross-sectional layer of the unitary mixer, and successively forming each layer of the unitary mixer by fusing a metallic powder. Exemplary embodiments are disclosed, showing unitary mixer comprising an annular housing and a swirler having a unitary construction wherein unitary mixer is made by using a rapid manufacturing process. In one aspect of the invention, the rapid manufacturing process is a laser sintering process.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application claims priority to U.S. Provisional Application Ser.No. 61/044,116, filed Apr. 11, 2008, which is herein incorporated byreference in its entirety.

BACKGROUND OF THE INVENTION

This invention relates generally to combustors, and more specifically tomixers used for enhancing fuel/air mixing in gas turbine enginecombustors.

Modern day emphasis on minimizing the production and discharge of gasesthat contribute to smog and to other undesirable environmentalconditions, particularly those gases that are emitted from gas turbineengines, have led to different combustor designs that have beendeveloped in an effort to reduce the production and discharge of suchundesirable combustion product components. Other factors that influencecombustor design are the desires of users of gas turbine engines forefficient, low cost operation, which translates into a need for reducedfuel consumption while at the same time maintaining or even increasingengine output. As a consequence, important design criteria for aircraftgas turbine engine combustion systems include provision for highcombustion temperatures, in order to provide high thermal efficiencyunder a variety of engine operating conditions, as well as theminimization of undesirable combustion conditions that contribute to theemission of particulates, and to the emission of undesirable gases, andto the emission of combustion products that are precursors to theformation of photochemical smog.

Various governmental regulatory bodies have established emission limitsfor acceptable levels of unburned hydrocarbons (HC), carbon monoxide(CO), and oxides of nitrogen (NOx), which have been identified as theprimary contributors to the generation of undesirable atmosphericconditions. Therefore, different combustor designs have been developedto meet those criteria. For example, one way in which the problem ofminimizing the emission of undesirable gas turbine engine combustionproducts has been attacked is the provision of staged combustion. Inthat arrangement, a combustor is provided in which a first stage burneris utilized for low speed and low power conditions to more closelycontrol the character of the combustion products. A combination of firststage and second stage burners is provided for higher power outletconditions while attempting to maintain the combustion products withinthe emissions limits. It will be appreciated that balancing theoperation of the first and second stage burners to allow efficientthermal operation of the engine, while simultaneously minimizing theproduction of undesirable combustion products, is difficult to achieve.In that regard, operating at low combustion temperatures to lower theemissions of NOx, can also result in incomplete or partially incompletecombustion, which can lead to the production of excessive amounts of HCand CO, in addition to producing lower power output and lower thermalefficiency. High combustion temperature, on the other hand, althoughimproving thermal efficiency and lowering the amount of HC and CO, oftenresults in a higher output of NOx. In the art, one of the ways in whichproduction of undesirable combustion product components in gas turbineengine combustors is minimized over the engine operating regime is byusing a staged combustion system using primary and secondary fuelinjection ports.

Another way that has been proposed to minimize the production of thoseundesirable combustion product components is to provide for moreeffective intermixing of the injected fuel and the combustion air. Inthat regard, numerous mixer designs have been proposed over the years toimprove the mixing of the fuel and air. In this way, burning occursuniformly over the entire mixture and reduces the level of HC and COthat result from incomplete combustion.

One mixer design that has been utilized is known as a twin annularpremixing swirler (TAPS), which is disclosed in the following U.S. Pat.Nos. 6,354,072; 6,363,726; 6,367,262; 6,381,964; 6,389,815; 6,418,726;6,453,660; 6,484,489; and, 6,865,889. It will be understood that theTAPS mixer assembly includes a pilot mixer which is supplied with fuelduring the entire engine operating cycle and a main mixer which issupplied with fuel only during increased power conditions of the engineoperating cycle. Improvements in the main mixer of the assembly duringhigh power conditions (i.e., take-off and climb) are disclosed in patentapplications having Ser. Nos. 11/188,596, 11/188,598, and 11/188,470.

The mixers have swirler assemblies that swirl the air passing throughthem to promote mixing of air with fuel prior to combustion. The swirlerassemblies used in the combustors are complex structures having axial,radial or conical swirlers or a combination of them. In the past,conventional manufacturing methods have been used to fabricate mixershaving swirler components that are assembled or joined together usingknown methods to form the swirler assemblies. For example, in somemixers with complex vanes, individual vanes are first machined and thenbrazed into an assembly. Investment casting methods have been used inthe past in producing some combustor swirlers. Other swirlers have beenmachined from raw stock. Electro-discharge machining (EDM) has been usedas a means of machining the vanes in the swirlers.

Conventional combustor components such as, for example, mixers, aregenerally expensive to fabricate and/or repair because the conventionalmixer designs include a complex assembly and joining of severalcomponents. More specifically, the use of braze joints can increase thetime needed to fabricate such mixers and can also complicate thefabrication process for any of several reasons, including: the need foran adequate region to allow for braze alloy placement; the need forminimizing unwanted braze alloy flow; the need for an acceptableinspection technique to verify braze quality; and, the necessity ofhaving several braze alloys available in order to prevent the re-meltingof previous braze joints. Moreover, numerous braze joints may result inseveral braze runs, which may weaken the parent material of thecomponent. The presence of numerous braze joints can undesirablyincrease the weight and manufacturing cost of the mixer assemblies.

Complexities of the swirler geometries and the associated difficultiesin the machining and normal wear of the tools such as the EDM electrodesduring the machining process, cause significant manufacturingvariability in the mixer assemblies. Such manufacturing variability inthe mixer assemblies may lead to undesirable aerodynamic flowvariability in the mixers and adversely impact the aerodynamicperformance of the combustor.

Thus, there is a need to provide a gas turbine engine combustor mixerusing a manufacturing method with reduced variability. Further, it isdesirable to have mixers with complex geometries and swirlerarrangements having a unitary construction to reduce dimensionalvariations from manufacturing to improve operability and reduceemissions over the engine's operating envelope and to reduce costs. Itis desirable to have a method of manufacturing a mixer having complexthree dimensional geometries in a unitary construction.

BRIEF DESCRIPTION OF THE INVENTION

The above-mentioned need or needs may be met by exemplary embodimentswhich provide a method for fabricating a mixer having a unitaryconstruction, said method comprising the steps of determiningthree-dimensional information of the unitary mixer having at least oneswirler, converting the three-dimensional information into a pluralityof slices that each define a cross-sectional layer of the unitary mixer,and successively forming each layer of the unitary mixer by fusing ametallic powder. Exemplary embodiments are disclosed, showing unitarymixers comprising an annular housing and a swirler having a unitaryconstruction wherein unitary mixer is made by using a rapidmanufacturing process. In one aspect of the invention, the rapidmanufacturing process is a laser sintering process.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter which is regarded as the invention is particularlypointed out and distinctly claimed in the concluding part of thespecification. The invention, however, may be best understood byreference to the following description taken in conjunction with theaccompanying drawing figures in which:

FIG. 1 is a diagrammatic view of a high bypass turbofan gas turbineengine.

FIG. 2 is a partial isometric view of a unitary mixer according to anexemplary embodiment of the present invention located on a fuel nozzleassembly.

FIG. 3 is an isometric view of a unitary mixer according to an exemplaryembodiment of the present invention.

FIG. 4 is an isometric cross sectional view of a unitary mixer accordingto the exemplary embodiment of the present invention shown in FIG. 3.

FIG. 5 is a side cross sectional view of the exemplary embodiment of thepresent invention of a unitary mixer shown in FIG. 3.

FIG. 6 is a frontal cross sectional view of the exemplary embodiment ofthe present invention shown in FIG. 3.

FIG. 7 is a frontal cross sectional view of the exemplary embodiment ofthe present invention shown in FIG. 3.

FIG. 8 is an isometric view of a unitary mixer according to an alternateexemplary embodiment of the present invention.

FIG. 9 is an isometric cross sectional view of the alternate exemplaryembodiment of the present invention shown in FIG. 3.

FIG. 10 is a frontal cross sectional view of the alternate exemplaryembodiment of the present invention shown in FIG. 8.

FIG. 11 is a frontal cross sectional view of the alternate exemplaryembodiment of the present invention shown in FIG. 8.

FIG. 12 is a frontal cross sectional view of the alternate exemplaryembodiment of the present invention shown in FIG. 8.

FIG. 13 is an isometric view of a unitary mixer according to analternate exemplary embodiment of the present invention.

FIG. 14 is an isometric cross sectional view of the alternate exemplaryembodiment of the present invention shown in FIG. 13.

FIG. 15 is a frontal cross sectional view of the alternate exemplaryembodiment of the present invention shown in FIG. 13.

FIG. 16 is a flow chart showing an exemplary embodiment of a method forfabricating a mixer having a unitary construction.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings in detail, wherein identical numeralsindicate the same elements throughout the figures, FIG. 1 depicts indiagrammatic form an exemplary gas turbine engine 10 (high bypass type)having a longitudinal or axial centerline axis 12 therethrough forreference purposes. Engine 10 preferably includes a core gas turbineengine generally identified by numeral 14 and a fan section 16positioned upstream thereof. Core engine 14 typically includes agenerally tubular outer casing 18 that defines an annular inlet 20.Outer casing 18 further encloses and supports a booster 22 for raisingthe pressure of the air that enters core engine 14 to a first pressurelevel. A high pressure, multi-stage, axial-flow compressor 24 receivespressurized air from booster 22 and further increases the pressure ofthe air. The pressurized air flows to a combustor 26, where fuel isinjected into the pressurized air stream and ignited to raise thetemperature and energy level of the pressurized air. The high energycombustion products flow from combustor 26 to a first (high pressure)turbine 28 for driving the high pressure compressor 24 through a first(high pressure) drive shaft 30, and then to a second (low pressure)turbine 32 for driving booster 22 and fan section 16 through a second(low pressure) drive shaft 34 that is coaxial with first drive shaft 30.After driving each of turbines 28 and 32, the combustion products leavecore engine 14 through an exhaust nozzle 36 to provide at least aportion of the jet propulsive thrust of the engine 10.

Fan section 16 includes a rotatable, axial-flow fan rotor 38 that issurrounded by an annular fan casing 40. It will be appreciated that fancasing 40 is supported from core engine 14 by a plurality ofsubstantially radially-extending, circumferentially-spaced outlet guidevanes 42. In this way, fan casing 40 encloses fan rotor 38 and fan rotorblades 44. Downstream section 46 of fan casing 40 extends over an outerportion of core engine 14 to define a secondary, or bypass, airflowconduit 48 that provides additional jet propulsive thrust.

From a flow standpoint, it will be appreciated that an initial air flow,represented by arrow 50, enters gas turbine engine 10 through an inlet52 to fan casing 40. Air flow 50 passes through fan blades 44 and splitsinto a first compressed air flow (represented by arrow 54) that movesthrough conduit 48 and a second compressed air flow (represented byarrow 56) which enters booster 22.

The pressure of second compressed air flow 56 is increased and entershigh pressure compressor 24, as represented by arrow 58. After mixingwith fuel and being combusted in combustor 26, combustion products 60exit combustor 26 and flow through first turbine 28. Combustion products60 then flow through second turbine 32 and exit exhaust nozzle 36 toprovide at least a portion of the thrust for gas turbine engine 10.

The combustor 26 includes an annular combustion chamber 62 that iscoaxial with longitudinal axis 12, as well as an inlet 64 and an outlet66. As noted above, combustor 26 receives an annular stream ofpressurized air from a high pressure compressor discharge outlet 69. Aportion of this compressor discharge air flows into a mixer 100, suchas, for example, shown in FIG.2. In the exemplary embodiment shown inFIG.2, air enters into the mixer 100 in a radial-circumferentialdirection (as represented by arrows 102, 104) and in an axial direction(as represented by arrow 106). Fuel is injected from a fuel nozzle tipassembly 68 to mix with the air and form a fuel-air mixture that isprovided to combustion chamber 62 for combustion. Ignition of thefuel-air mixture is accomplished by a suitable igniter, and theresulting combustion gases 60 flow in an axial direction toward and intoan annular, first stage turbine nozzle 72. Nozzle 72 is defined by anannular flow channel that includes a plurality of radially-extending,circumferentially-spaced nozzle vanes 74 that turn the gases so thatthey flow angularly and impinge upon the first stage turbine blades offirst turbine 28. As shown in FIG. 1, first turbine 28 preferablyrotates high pressure compressor 24 via first drive shaft 30. Lowpressure turbine 32 preferably drives booster 24 and fan rotor 38 viasecond drive shaft 34.

Combustion chamber 62 is housed within engine outer casing 18. Fuel issupplied into the combustion chamber by a fuel nozzle assembly 80, shownin FIG. 2. Fuel is supplied through fuel supply conduits located withina stem 82 to a fuel nozzle tip assembly 68. The mixer 100circumferentially surrounds the fuel nozzle tip assembly 68. Primary(pilot) and secondary fuel is sprayed by the fuel nozzle tip assembly68, using conventional means.

FIG. 2 shows an isometric view of the exemplary embodiment of the mixer100 having a unitary construction shown in FIG. 1. The term “unitary” isused in this application to denote that the associated component, suchas the mixer 100 200, 300 described herein, is made as a single pieceduring manufacturing. Thus, a unitary component has a monolithicconstruction for the entire component, and is different from a componentthat has been made from a plurality of component pieces that have beenjoined together to form a single component. The unitary mixer 100includes an annular main housing 120 (see FIG. 3) that radiallysurrounds the fuel nozzle tip assembly 68 (see FIG. 1) and defining anannular cavity between the housing 120 and the fuel nozzle tip assembly68. A plurality of fuel injection ports (not shown) introduce fuel intoannular cavity between the housing 120 and the fuel nozzle tip assembly68. The exemplary embodiment of the mixer 100 shown FIG. 2 comprises aswirler arrangement identified generally by numeral 130.

Swirler arrangement 130 may be configured in any of several ways, suchas, for example, shown in exemplary embodiments of unitary mixers 100,200, 300 shown herein in FIG. 3, FIG. 8 and FIG. 13 respectively. Apatent application entitled “Mixer Assembly For Combustor Of A GasTurbine Engine Having A Plurality Of Counter-Rotating Swirlers” havingSer. No. 11/188,596 and a patent application entitled “SwirlerArrangement For Mixer Assembly Of A Gas Turbine Engine Combustor HavingShaped Passages” having Ser. No. 11/188,595, both of which are assignedto the owner of the present invention show exemplary swirlerarrangements.

As shown in FIGS. 3-7, the unitary mixer 100 (i.e., mixer 100 having aunitary construction) comprises a swirler arrangement 130 having atleast one swirler, such as, for example, numeral item 140 shown in FIG.3. In a preferred embodiment of the mixer shown in FIGS. 3-7, unitarymixer 100 comprises a swirler arrangement 130 having three swirlers 140,160, 180, located in a housing 120. The unitary mixer 100 has an annularconstruction around an axis 111 having a radially inner hub 122, a rim124 located radially outwardly from the hub 122. The unitary mixer 100has a mount system 125 comprising an annular flange 126 that is locatedat one end of the mixer. The flange is used to locate the unitary mixer100 within the annular combustor 26. At least one pair of tabs 128 maybe located on the flange 126. The tabs 128 are used to orient and locatemixer 100 circumferentially in the combustor 26 and facilitates to reactthe mechanical and aerodynamic loads and moments induced in the mixer100. Assembling of mixers circumferentially around annular combustorshas been described in the following U.S. Pat. Nos. 7,062,920; 7,121,095;and 6,976,363, and the U.S. Patent Application publication US2007/0028620A1.

In the exemplary embodiment of the unitary mixer 100 shown in FIGS. 3-7,the first swirler 140 comprises a plurality of axial vanes 142 that arearranged circumferentially around the mixer axis 111. The axial vanes142 extend in the radial direction from the hub 122 to the rim 124. Theaxial vanes 142 extend generally in the axial direction with respect tothe axis 111 from a first location 144 (entrance location) to a secondlocation 146 (exit location). As seen in FIG. 5, the axial vanes 142 arearranged circumferentially around the mixer axis 111 such thatcircumferentially adjacent vanes 151, 152 form passages 154, 156 betweenthem, through which air flows into the mixer 100, as represented by airflow direction arrows 106.

Although it is possible to have the same geometry and orientation forall the axial vanes 142 in the swirler 140, it is not necessary to doso. In the preferred embodiment shown in FIG. 5, the swirler 140comprises circumferentially adjacent axial vanes 151 and 152 that havedifferent thickness variations in the axial direction such that a firstflow passage 154 and a second flow passage 156 are formed on each sideof the axial vanes 151 and 152. The first flow passage 154 has anorientation angle “A” and the second flow passage 156 has a secondorientation angle “B” with respect to the mixer axis 111. The variationof the flow area in the axial direction for each of the flow passages154 and 156 can be suitably designed by varying the thicknessdistribution of the adjacent vanes 151 and 152. In a preferredembodiment of the mixer, the thickness distribution for the axial vanes151 and 152 are such that the adjacent flow passages 154 and 156 have analternating converging-diverging characteristic: i.e., flow passage 154has a progressively smaller flow area (“converging”) in the axialdirection and flow passage 156 has a progressively larger area(“diverging”) in the axial direction. It is known that subsonic airflowing through a converging flow path is accelerated whereas subsonicair flowing through a diverging flow path is decelerated. Alternativelyvarying the flow passage areas between adjacent flow passages 154, 156facilitates intense mixing of the air and fuel inside the mixer 100. Itis also possible to have other suitable geometric variations in theadjacent flow passages 154, 156, such as for example, a converging flowpassage on one side of an axial vane 154, 152 and a constant flowpassage on the other side of the axial vane 154, 152. It is alsopossible to have different orientation angles “A” and “B” with respectto the axis 111 for two adjacent flow passages 151 and 152. Theexemplary embodiment shown in FIGS. 3-7 comprises a swirler 140 havingabout 36 to 50 axial vanes 142 arranged in the circumferentialdirection, having two orientation angles “A” and “B”. In the exemplaryembodiment shown in FIG. 5, the orientation angles “A” and “B”preferably have values of approximately 65 degrees and 50 degreesrespectively, and the flow passage 154 converges about 80% in the axialdirection and the flow passage 156 diverges about 50% in the axialdirection.

The exemplary embodiment of a unitary mixer 100 shown in FIGS. 3-7comprises a second swirler 160 that is located axially aft from thefirst swirler 140. A cross sectional view of the second swirler 160perpendicular to the mixer axis 111 is shown in FIG. 6. It will be notedthat second swirler 160 includes a plurality of radial vanes 162 forswirling the air flowing therebetween. As shown, the second swirler 160having radial vanes 162 is preferably oriented substantially radially tocenterline axis 111 through mixer 100. Air flows into the mixer 100through flow passages 176 between adjacent radial vanes 171, 172 in asubstantially radially inward direction, as shown by air flow arrow 104.In the exemplary embodiment shown in FIG. 6, radial vanes 162 aresubstantially uniformly spaced circumferentially and a plurality ofsubstantially uniform passages 176 are defined between adjacent radialvanes such as, for example, items 171, 172 in FIG. 6. Although radialvanes 162 are shown as being substantially uniformly spacedcircumferentially, thereby defining a plurality of substantially uniformpassages therebetween, it will further be understood that swirler 160may include radial vanes 162 having different configurations so as toshape the passages 176 in a desirable manner, such as, for example, asdisclosed in the '595 patent application identified hereinabove. In theexemplary embodiment shown in FIG. 6, the second swirler 160 has about36 to 50 radial vanes 162. Radial vanes 162 are oriented such that theflow passage formed between two adjacent radial vanes 171, 172 has anorientation angle “C” with respect to a line 115 perpendicular to themixer axis 111 and passing through the center 175 of the passage whereair flow 104 enters the mixer 100. In the exemplary embodiment shown inFIG. 6, the orientation angle “C” is preferably between about 30-70degrees.

The exemplary embodiment of a unitary mixer 100 shown in FIGS. 3-7comprises a third swirler 180 that is located axially aft from thesecond swirler 160. A cross sectional view of the second swirler 180perpendicular to the mixer axis 111 is shown in FIG. 7. It will be notedthat third swirler 180 includes a plurality of radial vanes 182 forswirling the air flowing therebetween. As shown, the third swirler 180having radial vanes 182 is preferably oriented generally in theradial-tangential direction with respect to centerline axis 111 throughmixer 100. Air flows into the mixer 100 through flow passages 196between adjacent radial vanes 191, 192 in a generally radially inwarddirection having a substantial tangential orientation, as shown by airflow arrow 102. In the exemplary embodiment shown in FIG. 7, radialvanes 182 are substantially uniformly spaced circumferentially and aplurality of substantially uniform passages 196 are defined betweenadjacent radial vanes such as, for example, items 191, 192 in FIG. 7.Although radial vanes 182 are shown as being substantially uniformlyspaced circumferentially, thereby defining a plurality of substantiallyuniform passages therebetween, it will further be understood thatswirler 180 may include radial vanes 182 having different configurationsso as to shape the passages 196 in a desirable manner. In the exemplaryembodiment shown in FIG. 7, the third swirler 180 has about 30 to 50radial vanes 182. Radial vanes 182 are oriented such that the flowpassage formed between two adjacent radial vanes 191, 192 has anorientation angle “D” with respect to a line 117 perpendicular to themixer axis 111 and passing through the center 195 of the passage whereair flow 102 enters the mixer 100. In the exemplary embodiment shown inFIG. 7, the orientation angle “D” is preferably between about 0-60degrees.

It will be understood that air flowing through second swirler 160 willbe swirled in a first direction and air flowing through third swirler180 will preferably be swirled in a direction opposite the firstdirection. This is accomplished by appropriately choosing theorientation angles “C” and “D” for the air flow passages 176 and 196respectively. In this way, an intense mixing of air and fuel isaccomplished within combustor having an enhanced total kinetic energy.By properly configuring swirlers 140, 160 and 180, an intense mixingregion can be substantially centered within annular cavity around thefuel nozzle tip assembly 68. The configuration of the vanes in swirlers140, 160 and 180 may be altered to vary the swirl direction of airflowing therethrough and not be limited to the exemplary swirldirections indicated hereinabove.

It will be seen in FIGS. 3-5 that, with respect to the mixer axis 111,the axial length of radial vanes 182 of the third swirler 180 ispreferably greater than the axial length of radial vanes 162 of thesecond swirler 160. Accordingly, a relatively greater amount of airflows through third swirler 180 than through second swirler 160 due tothe greater passage area therefor. The relative axial lengths ofswirlers 180 and 160 may be varied as desired to alter the distributionof air therethrough, so the sizes depicted are only illustrative.

An alternative exemplary embodiment of a unitary mixer 200 is shown inFIGS. 8-12. It will be seen in FIGS. 8-12 that the exemplary unitarymixer 200 comprises a swirler arrangement 230 having first, second andthird swirlers 240, 260 and 280, respectively. FIG. 9 shows an isometriccross sectional view of the unitary mixer 200. The first swirler 240 isa radial swirler, which is different from the axial swirler 140 shown inFIG. 3 and described previously herein. A cross sectional view of thefirst swirler 240 taken perpendicular to the mixer axis 111 is shown inFIG. 10. The second swirler 260 is located axially aft from the firstswirler 240, and is a radial swirler generally similar to the radialswirler 160 shown in FIG. 6 described previously herein. A crosssectional view of the second swirler 260 taken perpendicular to themixer axis 111 is shown in FIG. 11. The third swirler 280 is locatedaxially aft from the second swirler 260, and is a radial swirlergenerally similar to the radial swirler 180 shown in FIG. 7 describedpreviously herein. A cross sectional view of the third swirler 280 takenperpendicular to the mixer axis 111 is shown in FIG. 12. It will beunderstood that, as shown in FIGS. 10, 11 and 12, air flowing throughthe first swirler 240, will be swirled in a first direction and airflowing through the second swirler 260 will preferably be swirled in adirection opposite the first direction, and the air flowing through thethird swirler 280 will preferably be swirled in a direction opposite thesecond direction This is accomplished by appropriately choosing theorientation angles for the air flow passages 254, 276 and 296respectively. Although radial vanes 242, 262 and 282 are shown in FIGS.10, 11 and 12 as being substantially uniformly spaced circumferentially,thereby defining a plurality of substantially uniform passagestherebetween, it will further be understood that swirlers 240, 260 and280 may include radial vanes 242, 262, 282 having differentconfigurations so as to shape the air flow passages betweencircumferentially adjacent radial vanes in a desirable manner. Theunitary mixer 200 has a mount system 225 comprising an annular flange226 and at least one pair of tabs 228 used to locate the unitary mixer200 within the annular combustor 26 as described previously herein.

Another alternative exemplary embodiment of a unitary mixer 300 is shownin FIGS. 13-15. It will be seen in FIGS. 13-15 that the exemplaryunitary mixer 300 comprises a swirler arrangement 330. A cross sectionalview of the swirler 330 perpendicular to the mixer axis 111 is shown inFIG. 15. The swirler 330 comprises radial vanes 382 arrangedcircumferentially around the mixer axis 111. Adjacent radial vanes 382form a flow passage 396 between them. Air flows into the unitary mixer300 through these passages in a generally radial-tangential direction,as represented by an arrow 302 in FIG. 15. The orientation angles forthese radial vanes are similar to those for the radial vanes in theunitary mixers 100, 200 described previously herein. Although radialvanes 382 are shown in FIG. 15 as being substantially uniformly spacedcircumferentially, thereby defining a plurality of substantially uniformpassages 396 therebetween, it will further be understood that swirler330 may include radial vanes 382 having different configurations so asto shape the air flow passages between circumferentially adjacent radialvanes in a desirable manner. The unitary mixer 300 has a mount system325 comprising an annular flange 326 and at least one pair of tabs 328used to locate the unitary mixer 300 within the annular combustor 26 asdescribed previously herein.

Other embodiments for the swirler arrangements may be utilized in theunitary mixers 100, 200 and 300, as disclosed in patent applicationsentitled, “Mixer Assembly For Combustion Chamber Of A Gas Turbine EngineHaving A Plurality Of Counter-Rotating Swirlers” having Ser. No.11/188596, “Swirler Arrangement For Mixer Assembly Of A Gas TurbineEngine Combustor Having Shaped Passages” having Ser. No. 11/188595, and“Mixer Assembly For Combustor Of A Gas Turbine Engine Having A MainMixer With Improved Fuel Penetration” having Ser. No. 11/188598.

Use of Rapid Manufacturing methods, such as, for example, Direct MetalLaser Sintering (DMLS), provides a manufacturing method that providesthe capability of producing parts without custom molds and/or specialtooling, like investment casting methods. Use of rapid manufacturingmethods such as DMLS provides the capability to produce unitary mixers100, 200, 300 having complex swirlers 130, 230, 330 and vane shapes thatpreviously could not be produced using conventional machining or evenEDM machining using multiple custom electrodes due to insufficientaccess on the inner diameter of the parts. The DMLS process usespowdered metal technology. The part being manufactured is modeled in athree-dimensional CAD model and geometrical data is broken into layersas small as 0.0004 inches. Conventional CAD software can be used forthis purpose. Metal powder is deposited per the geometry definitiondefined for a specific layer. A laser is then used to sinter the powderto the layers underneath the current layer. Platforms and/or columns areused as a base for the first layer of powder and for support for largevoids in the geometry. After completing the DMLS process, the platformsand/or support columns can be machined off using conventional machiningmethods. Use of rapid manufacturing processes, such as the DMLS process,provides the capability of producing complex unitary mixers, such asitems 100, 200, 300 shown herein, having complex three-dimensionalswirlers with swept aerodynamic vane shapes, with reduced part-to-partvariability.

The exemplary embodiment of a unitary mixer 100 shown in FIG. 3 and thealternative embodiments of the unitary mixer 200, 300 shown in FIGS. 8and 13 can be made using rapid manufacturing processes such as DirectMetal Laser Sintering (DMLS), Laser Net Shape Manufacturing (LNSM),electron beam sintering and other known processes in rapidmanufacturing. DMLS is a preferred method of rapid manufacturing unitarymixers such as the items 100, 200, 300 described herein.

FIG. 16 is a flow chart illustrating an exemplary embodiment of a rapidmanufacturing method 500 for fabricating unitary mixers such as items100, 200, 300 shown in FIGS. 3, 8 and 13, and described herein. Method500 includes fabricating unitary mixer 100, 200, 300 using Direct MetalLaser Sintering (DMLS). DMLS is a known manufacturing process thatfabricates metal components using three-dimensional information, forexample a three-dimensional computer model, of the component. Thethree-dimensional information for the unitary mixer 100, 200, 300 isconverted into a plurality of slices, each slice defining a crosssection of the unitary mixer for a predetermined height of the slice.The unitary mixer is then “built-up” slice by slice, or layer by layer,until finished. Each layer of the unitary mixer is formed by fusing ametallic powder using a laser.

Accordingly, method 500 includes the step 505 of determiningthree-dimensional geometric and other information of the unitary mixer100, 200, 300 (shown in FIG. 3, FIG. 8 and FIG. 13) and the step 210 ofconverting the three-dimensional information into a plurality of slicesthat each define a cross-sectional layer of the unitary mixer 100, 200,300. The unitary mixer 100, 200, 300 is then fabricated using DMLS, ormore specifically, each layer of the unitary mixer 100, 200, 300 issuccessively formed (step 515) by fusing a metallic powder using laserenergy. Each layer has a size between about 0.0005 inches and about0.001 inches. Unitary mixer 100, 200, 300 may be fabricated using anysuitable laser sintering machine. Examples of suitable laser sinteringmachines include, but are not limited to, an EOSINT.RTM. M 270 DMLSmachine, a PHENIX PM250 machine, and/or an EOSINT.RTM. M 250 XtendedDMLS machine, available from EOS of North America, Inc. of Novi, Mich.The metallic powder used to fabricate the unitary mixer 100, 200, 300 ispreferably a powder including cobalt chromium, but may be any othersuitable metallic powder, such as, but not limited to, HS188 andINCO625. The metallic powder can have a particle size of between about10 microns and 74 microns, preferably between about 15 microns and about30 microns. In the exemplary embodiments of the unitary mixer 100, 200,300 disclosed herein, a EOSINT 270 laser sintering system using a 200 WYtterbium Fiber laser in an Argon atmosphere was used.

Although the methods of manufacturing unitary mixers 100, 200, 300 havebeen described herein using DMLS as the preferred method, those skilledin the art of manufacturing will recognize that any other suitable rapidmanufacturing methods using layer-by-layer construction or additivefabrication can also be used. These alternative rapid manufacturingmethods include, but not limited to, Selective Laser Sintering (SLS),Selective Laser Melting (SLM), 3D printing, such as by inkjets andlaserjets, Sterolithography (SLS), Direct Selective Laser Sintering(DSLS), Electron Beam Sintering (EBS), Electron Beam Melting (EBM),Laser Engineered Net Shaping (LENS), Laser Net Shape Manufacturing(LNSM), Direct Metal Deposition (DMD), Solid Free Form Fabrication (SFF)and Layer Manufacturing.

When introducing elements/components/etc. of the methods and/or unitarymixers described and/or illustrated herein, the articles “a”, “an”,“the” and “said” are intended to mean that there are one or more of theelement(s)/component(s)/etc. The terms “comprising”, “including” and“having” are intended to be inclusive and mean that there may beadditional element(s)/component(s)/etc. other than the listedelement(s)/component(s)/etc.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to make and use the invention. The patentable scope of the inventionis defined by the claims, and may include other examples that occur tothose skilled in the art. Such other examples are intended to be withinthe scope of the claims if they have structural elements that do notdiffer from the literal language of the claims, or if they includeequivalent structural elements with insubstantial differences from theliteral languages of the claims.

1. A method for fabricating a unitary mixer, said method comprising thesteps of: determining three-dimensional information of the unitary mixerhaving at least one swirler; converting the three-dimensionalinformation into a plurality of slices that each define across-sectional layer of the unitary mixer; and successively formingeach layer of the unitary mixer by fusing a metallic powder using laserenergy.
 2. A method in accordance with claim 1 wherein determiningthree-dimensional information of the unitary mixer further comprisesdetermining a three-dimensional model of the unitary mixer.
 3. A methodin accordance with claim 1 wherein successively forming each layer ofthe unitary mixer by fusing a metallic powder using laser energy furthercomprises fusing a powder comprising at least one of cobalt chromium,HS188 and INCO
 625. 4. A method in accordance with claim 1 whereinsuccessively forming each layer of the unitary component by fusing ametallic powder using laser energy further comprises fusing a metallicpowder that has a particle size between about 10 microns and about 75microns.
 5. A method in accordance with claim 4 wherein successivelyforming each layer of the unitary component by fusing a metallic powderusing laser energy further comprises fusing a metallic powder that has aparticle size between about 15 microns and about 30 microns.
 6. A methodin accordance with claim 1 wherein determining three-dimensionalinformation of the unitary mixer further comprises determining athree-dimensional model of the unitary mixer having a plurality ofpassages arranged circumferentially around an axis.
 7. A method inaccordance with claim 1 wherein determining three-dimensionalinformation of the unitary component further comprises determining athree-dimensional model of the unitary mixer having a plurality ofpassages arranged circumferentially around an axis.
 8. A method inaccordance with claim 1 wherein determining three-dimensionalinformation of the unitary component further comprises determining athree-dimensional model of the unitary mixer having a plurality of vanesarranged circumferentially around an axis.
 9. A method in accordancewith claim 1 wherein the unitary mixer comprises an annular housing anda swirler having a plurality of vanes.
 10. A method in accordance withclaim 1 wherein the unitary mixer comprises an annular housing and aplurality of swirlers having a plurality of vanes.
 11. A unitary mixercomprising an annular housing and a swirler having a unitaryconstruction wherein unitary mixer is made by using a rapidmanufacturing process.
 12. A unitary mixer according to claim 11 whereinthe rapid manufacturing process is a laser sintering process.
 13. Aunitary mixer according to claim 11 wherein the rapid manufacturingprocess is DMLS.
 14. A unitary mixer according to claim 11 wherein theswirler comprises a plurality of vanes arranged circumferentially aroundthe axis.
 15. A unitary mixer according to claim 11 wherein the swirlercomprises a plurality of vanes arranged circumferentially around theaxis such that circumferentially adjacent vanes form at least one flowpassage that is oriented at least partially in an axial direction withrespect to the axis.
 16. A unitary mixer according to claim 15 whereinat least one flow passage is converging in a flow direction.
 17. Aunitary mixer according to claim 11 further comprising a mount systemfor mounting the unitary mixer in a combustor.
 18. A unitary mixeraccording to claim 11 wherein the swirler comprises a plurality ofradial vanes arranged circumferentially around the axis.
 19. A unitarymixer according to claim 11 further comprising a plurality of swirlers.20. A unitary mixer according to claim 19 further wherein the pluralityof swirlers comprise a plurality of radial vanes.